lists.openwall.net   lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  linux-cve-announce  PHC 
Open Source and information security mailing list archives
 
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <d585f337-5ce7-4a02-b890-5f3888e59ad0@amd.com>
Date: Mon, 17 Feb 2025 22:01:14 +0530
From: Ravi Bangoria <ravi.bangoria@....com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: "mingo@...nel.org" <mingo@...nel.org>,
 "lucas.demarchi@...el.com" <lucas.demarchi@...el.com>,
 "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
 "willy@...radead.org" <willy@...radead.org>,
 "acme@...nel.org" <acme@...nel.org>,
 "namhyung@...nel.org" <namhyung@...nel.org>,
 "mark.rutland@....com" <mark.rutland@....com>,
 "alexander.shishkin@...ux.intel.com" <alexander.shishkin@...ux.intel.com>,
 "jolsa@...nel.org" <jolsa@...nel.org>,
 "irogers@...gle.com" <irogers@...gle.com>,
 "adrian.hunter@...el.com" <adrian.hunter@...el.com>,
 "kan.liang@...ux.intel.com" <kan.liang@...ux.intel.com>,
 Ravi Bangoria <ravi.bangoria@....com>
Subject: Re: [PATCH v2 24/24] perf: Make perf_pmu_unregister() useable

On 17-Feb-25 1:54 PM, Ravi Bangoria wrote:
> Hi Peter,
> 
>>> Apparently not, it ends up with:
>>>
>>>   ------------[ cut here ]------------
>>>   WARNING: CPU: 145 PID: 5459 at kernel/events/core.c:281 event_function+0xd2/0xf0
>>>   WARNING: CPU: 145 PID: 5459 at kernel/events/core.c:286 event_function+0xd6/0xf0
>>
>>>    remote_function+0x4f/0x70
>>>    generic_exec_single+0x7f/0x160
>>>    smp_call_function_single+0x110/0x160
>>>    event_function_call+0x98/0x1d0
>>>    _perf_event_disable+0x41/0x70
>>>    perf_event_for_each_child+0x40/0x90
>>>    _perf_ioctl+0xac/0xb00
>>>    perf_ioctl+0x45/0x80
>>
>> Took me a long while trying to blame this on the 'event->parent =
>> NULL;', but AFAICT this is a new, unrelated issue.
>>
>> What I think happens is this perf_ioctl(DISABLE) vs pmu_detach_events()
>> race, where the crux is that perf_ioctl() path does not take
>> event2->mutex which allows the following interleave:
> 
> This one was only with perf_fuzzer, so pmu_detach_events() code path was
> not invoked.

I think the issue is, unaccount_event() gets called for the child event
after the child is detached. Since event->parent is NULL, unaccount_event()
abruptly corrupts the perf_sched_work.

I haven't verified it. Will do it tomorrow.

Thanks,
Ravi

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ